Add Gaussian Noise to Signal In C++

double AWGN_generator()
{

	/* Generates additive white Gaussian Noise samples with zero mean and a standard deviation of 1. */
	
	double temp1_d;
	double temp2_d;
	double result_d;
	int p_ui;

	p_ui = 1;

	while( p_ui > 0 )
		{
			temp2_d = ( rand() / ((double) RAND_MAX ) ); /*  rand() function generates an
																   integer between 0 and  RAND_MAX,
																   which is defined in stdlib.h.
																   */
			if ( temp2_d == 0 )
				{// temp2 is >= (RAND_MAX / 2)
					 p_ui = 1;
				} // end if
			else
				{// temp2 is < (RAND_MAX / 2)
					p_ui = -1;
				}// end else

		}// end while()

  temp1_d = cos( ( 2.0 * (double)PI ) * rand() / (double) ( RAND_MAX ) );
  result_d = sqrt( -2.0 * log( temp2_d ) ) * temp1_d;
	
  return result_d ;

}